“Premio Formazione” 2° congresso nazionale Multisala SivarSib

The project aimed to: - investigate the role of healthy and diseased dairy cattle as carriers of ESKAPE bacteria; - characterize their phenotypic antimicrobial resistance profiles; - assess potential zoonotic transmission risk by comparing strains isolated from animals and human operators. A prospective epidemiological study was carried out from July to September 2024 on 20 Friesian dairy cows, including both healthy and clinically diseased animals. Faeces, milk, and swabs from eye, oral, nasal, ear, and skin sites were collected, along with skin swabs from the operator’s hands after each sampling. Samples were processed at the Laboratory of Medical Microbiology and Infectious Diseases, University of Camerino, using selective culture media (Liofilchem, Italy). Bacterial identification was performed by MALDI-TOF MS (Bruker Daltonics, Germany-Flex Analysis software 3.4, Biotyper 3.1), and antimicrobial susceptibility testing was conducted using the Kirby-Bauer disk diffusion method and E-test against 38 veterinary and human antibiotics from 20 classes. Susceptible, resistant and multidrug-resistant (MDR) strains were interpreted according to CLSI VET01S (2024), EUCAST (2025), and Magiorakos et al. (2012). Statistical analysis employed Fisher's exact test, relative risk (RR), and attributable risk (AR), with P values<0.05 considered significant. From 148 samples, 796 microorganisms were isolated, including 133 (16.7%) ESKAPE bacteria. The most frequently detected were Enterobacter spp. (36.1%, 48/133), K. pneumoniae (30.8%, 41/133), E. coli (30.8%, 41/133), Acinetobacter spp. (12.8%, 17/133), PA (0.8%, 1/133), and S. aureus (0.8%, 1/133). ESKAPE isolation was significantly higher in Autumn (20.8% vs. 14.6%, P=0.025) and in diseased animals (21.2% vs. 10.7%, P=0.0001). No significant difference was observed between animal and operator hands isolates (17% vs. 12%, P=0.134). Isolation frequencies were similar across different animal body sites (1<1.38, AR=0.05). Among ESKAPE isolates, 56.6% (30/53) resulted MDR: KP (42.9%), showing 100% resistance to ampicillin and fosfomycin; Es (78%); EC (15.4%); Acinetobacter spp. (including A. baumannii) (70.6%), demonstrated resistance to third-generation cephalosporins, carbapenems, and monobactams; Pseudomonas spp. (100%), with PA resistant to tetracyclines, penicillins, first- to fourth-generation cephalosporins, and critically important antimicrobials (carbapenems, macrolides, monobactams). The same phenotypic resistance profile was observed for KP, EC, Enterococcus casseliflavus, Acinetobacter spp. and Pseudomonas spp. strains isolated from animals and operator hands.